1. Field of the Invention
The present invention generally relates to a liquid ejection head for delivering a liquid of a recording head used in an image recording apparatus such as a printer, a colorant ejection head used in fabricating a color filter of a liquid crystal display or the like, an organic EL display, an electrode material ejection head used for forming an electrode of a field emission display (FED) or the like, a living body organic substance ejection head used for fabricating a biochip or the like and a liquid ejection apparatus using the liquid ejection head.
2. Related Art
There is an ink jet printer widely used as a liquid ejection apparatus. The ink jet printer is provided with a recording head as a liquid ejection head for ejecting droplets of ink which is a liquid from a plurality of nozzle openings. The ink droplets are impacted to a surface of recording paper or the like which is a medium by the recording head to thereby print an image, a character or the like.
Such an ink jet printer is provided with a carriage moved relative to the recording paper or the like by a moving unit and the recording head is mounted to the carriage.
FIG. 25 is a schematic sectional view showing a structure assumed for functioning as a recording head mounted to such an ink jet printer and FIG. 26 is a view showing to enlarge a region designated by notation C of FIG. 25.
In the drawings, a recording head 1 is provided with a head case 2 and a circuit board B fixed to an upper face of the head case in the drawing. As shown by FIG. 26, the head case 2 is provided with a base portion 7 spread in a flange-like shape and a front end portion 6 extended integrally from the base portion 7 and projected in a lower direction of the drawing. The head case 2 is formed with a plurality of containing portions H1, H1, H1 arranged in parallel with a longitudinal direction by utilizing an inner portion of the front end portion 6.
As shown by FIG. 25, the containing portions H1, H1, H1 of the head case 2 are respectively fixed with oscillator units 4, 4, 4 as a device for driving nozzles. In details, as shown by FIG. 26, the oscillator unit 4 is provided with an attaching plate or a fixing plate 4a fixed to an inner face of the containing portion H1, an oscillator 4b arranged by fixing one end thereof to the fixing plate 4a and directing a free end thereof in the lower direction and a tape carrier 4c comprising a flexible board or the like one end of which is electrically connected to the oscillator 4b. Other end of the tape carrier 4c is connected to the circuit board B.
Meanwhile, a flow path unit 3 having a laminated layer structure in a plate-like shape is fixed to an end face of the front end portion 6 of the head case 2 and as shown by FIG. 25, the flow path unit 3 is formed with a plurality of nozzle openings 3a, 3a, 3a. Further, a head cover 5 comprising a metal material in a frame-like shape is arranged from an outer side of the flow path unit 3. The head cover 5 is provided with an opening portion 5a for exposing the nozzle openings 3a, 3a, 3a of the flow path unit 3 at a front end thereof, covers a side face of the front end portion 6 of the head case 2 by a protective wall portion 5b thereof and fixed to the base portion 7 of the head case 2 by utilizing a support portion 5c thereof bent to constitute a flange-like shape.
Thereby, the head cover 5 covers to protect the flow path unit 3 having a fine structure and a side face portion of the head case 2 and shields these parts by a grounding effect by the metal material.
The recording head 1 ejects ink guided to the flow path unit 3 by a means (not illustrated), by applying drive voltage from the circuit board B to the oscillator unit 4 as a driving device from the nozzle opening 3a by oscillation of each oscillator 4b. Thereby, predetermined printing is carried out on a print face or the like of a medium (not illustrated) of recording paper or the like.
After carrying out the printing, there is a case in which a small amount of ink is adhered to the surrounding or the like of the nozzle opening 3a of the flow path unit 3. Therefore, cleaning operation is carried out. As shown in FIG. 25, for example, the cleaning operation is carried out by making a wiping device 8 or the like provided to the ink jet printer relatively approach the recording head 1 as shown by an arrow A1 and moving a wiping face thereof relatively in an arrow A2 direction in a state of being brought into contact with the nozzle opening 3a to thereby wipe ink remaining at the surrounding of the nozzle opening 3a. 
However, according to the recording head 1, there is a case in which the small amount of ink wiped by the cleaning operation remains at a space S1 of FIG. 26. That is, in the cleaning operation, ink may be brought to an inner side of the head cover 5 and stored at an inner space of the space S1 or the like.
That is, the flow path unit 3 is fixed to an end face of the front end portion 6 of the head case 7 by using an adhesive agent and therefore, in order to take an adhering allowance thereof, an outer shape of the flow path unit 3 is necessarily smaller than an outer shape of the end face of the front end portion 6 of the head case 2. Therefore, the space S1 shown by FIG. 26 is necessarily formed at the inner side of the head cover 5.
Therefore, ink invading the inner side of the head cover 5 is stored at the space S1.
The ink stored at the space S1 is brought into a small clearance G1 between the protective wall portion 5b of the head cover 5 and a side wall of the front end portion 6 of the head case 2 by the capillary phenomenon, moved in a direction of an arrow A3, spread to a total of the clearance G1 between the protective wall portion 5b and the side face of the front end portion 6 of the head case 2 and is held by surface tension.
When the recording head 1 changes its attitude under the state, for example, when the recording head 1 is inclined skewedly in operation of carrying the recording head 1 by a user or the like a phenomenon shown in FIG. 27 is brought about.
FIG. 27 is a schematic perspective view viewing the structure of FIG. 25 from an outer side and an up and down direction is shown to be opposed to that of FIG. 25 for convenience of explanation.
In the drawing, although ink invading the small clearance G1 between the protective wall portions 5b, 5b contiguous to each other and the side walls of the front end portion 6 of the head case 2 is held in a total of inner faces thereof, when the recording head 1 is inclined such that portions contiguous to the respective protective wall portions 5b, 5b are disposed on the lower side, ink at the inner faces of the respective wall portions 5b, 5b is aggregated to the portions contiguous to the respective protective wall portions 5b, 5b as shown by arrows A10, A10 by its own weight. Therefore, the aggregated ink flows down along the end faces of the respective protective wall portions 5b, 5b and along directions of arrows A11, A11 and advances to the head case 2. The ink aggregated in this way to increase the weight is liable to flow and may be moved around to a rear face of the base portion 7 in FIG. 27 by conducting the base portion 7 in the flange-like shape and moved to the circuit board B to cause shortcircuit.
That is, according to the constitution shown by FIG. 25 and FIG. 26, the clearance G1 is continuous to the base portion 7 of the head case 2, the clearance between the base portion 7 and the support portion 5c of the head cover 5 is extremely small and therefore, the ink moved by the capillary phenomenon is moved up to the base portion 7 of the head case 2. When the recording head 1 changes its attitude under the state, for example, in the case of carrying the recording apparatus 100 by the user, when a main body of the apparatus or the recording head 1 is inclined, the ink stored at the space S1 and continuous to the base portion 7 of the head case 2 may be moved instantaneously to the circuit board B.